Download threatening substances

Project Comenius 2009:
Together Against Climate Change 2009
The primary goal of this project is to present the ozone depleting
substances and greenhouse gases that threaten the atmosphere
and influence the climate change.
1.
Atmosphere
2.
Greenhouse effect
3.
Climate Change
4.
Carbon Dioxide
5.
Water vapour
6.
Methane
7.
Nitrogen Oxide
8.
Chlorofluorocarbons
The
gaseous
envelope
surrounding the Earth. The dry
atmosphere
consists
almost
entirely of nitrogen (78.1% volume
mixing ratio) and oxygen (20.9%
volume mixing ratio), together
with a number of trace gases,
such as argon (0.93% volume
mixing
ratio),
helium,
radioactively active greenhouse
gases such as carbon dioxide Vertical division into:
(0.035% volume mixing ratio), and
ozone. In addition the atmosphere
contains water vapour, whose
amount is highly variable but
typically 1% volume mixing ratio.
The atmosphere also contains
clouds and aerosols
Carbon dioxide (and water) have
absorptions near 7 and 15 microns that
produce a greenhouse effect that warms
the earth to a comfortable temperature for
life as we know it. This picture shows how
it works. Sunlight is either absorbed or
reflected by the surface of the earth. The
absorbed part heats
the surface, and causes it to emit where
the 15 micron greenhouse effect operates.
Thus, some portion of the energy is
trapped and warms the surface above the
temperature for a planet without an
atmosphere.
From UCAR
Communications, http://www.ucar.edu/communications/newsreleases/2
001/learnweb.html
Climate change refers to any significant change in measures of climate (such as temperature, precipitation, or
wind) lasting for an extended period (decades or longer). Climate change may result from:
natural factors, such as changes in the sun's intensity or slow changes
in the Earth's orbit around the sun;
natural processes within the climate system
(e.g. changes in ocean circulation);
human activities that change the atmosphere's composition
(e.g. through burning fossil fuels) and the land surface
(e.g. deforestation, reforestation, urbanization, desertification, etc.)
The atmosphere keeps the Earth warmer by about 33 ºC without it the
temperature would be about –18 ºC, in reality it is about 15 ºC.
glacier Rhônegletscher, Switzerland
Any gas that absorbs infrared radiation in the atmosphere. Greenhouse gases
include, but are not limited to, water vapour, carbon dioxide (CO2), methane
(CH4),
nitrous
oxide
(N2O),
chlorofluorocarbons
(CFCs),
hydro
chlorofluorocarbons (HCFCs), ozone (O3 ), hydro fluorocarbons (HFCs), per
fluorocarbons (PFCs), and sulphur hexafluoride (SF6). The following focus is on
first five.
Methane
Carbon dioxide is one of the most abundant gasses in the atmosphere. Carbon dioxide plays an important
part in vital plant and animal process, such as photosynthesis and respiration. A naturally occurring gas,
and also a by-product of burning fossil fuels and biomass, as well as land-use changes and other
industrial processes. It is the principal anthropogenic greenhouse gas that affects the Earth's radiative
balance. It is the reference gas against which other greenhouse gases are measured and therefore has a
significant Global Warming Potential.
It is the gas without smell, with weakly sour taste, heavier than air, therefore it cumulates in lower layers
of spaces and rooms and its average content is 0.034%.
The concentration of carbon dioxide in the atmosphere has increased more in the northern hemisphere
where more fossil fuel burning occurs. Since the Industrial Revolution the concentration globally has
increased by 30%.
The future
The best case scenario for the increase in carbon dioxide emissions predicts that the concentration of
carbon dioxide in the atmosphere will reach double the level of before the Industrial Revolution, in 2100.
The worst case scenario brings this forward to 2045.
Carbon is the building block for all living things. The conversion of carbon dioxide into living matter and then back
is the main pathway of the carbon cycle. Plants draw about one quarter of the carbon dioxide out of the
atmosphere and photosynthesize it into carbohydrates. Some of the carbohydrate is consumed by plant
respiration and the rest is used to build plant tissue and growth. Animals consume the carbohydrates and return
carbon dioxide to the atmosphere during respiration. Carbohydrates are oxidized and returned to the atmosphere
by soil microorganisms decomposing dead animal and plant remains (soil respiration).
Another quarter of atmospheric carbon dioxide is
absorbed by the world’s oceans through direct airwater exchange. Surface water near the poles is cool
and more soluble for carbon dioxide. The cool water
sinks and couples to the ocean's thermohaline
circulation which transports dense surface water
toward the ocean's interior. Marine organisms form
tissue containing reduced carbon, and some also
form carbonate shells from carbon extracted from the
air.
There is actually very little of the total carbon cycling
through the Earth system at any one point in time.
Most of the carbon is stored in geologic deposits carbonate rocks, petroleum, and coal - formed from
the burial and compaction of dead organic matter on
sea bottoms. The carbon in these deposits is
normally released by rock weathering.
Figure ES.15 The Carbon Cycle
Courtesy NASA
Source: http://earthobservatory.nasa.gov/Library/CarbonCycle/carbon_cycle4.html
The most abundant greenhouse gas, it is the water present in the atmosphere in gaseous form. Water
vapor is an important part of the natural greenhouse effect. While humans are not significantly increasing
its concentration, it contributes to the enhanced greenhouse effect because the warming influence of
greenhouse gases leads to a positive water vapor feedback. In addition to its role as a natural greenhouse
gas, water vapor plays an important role in regulating the temperature of the planet because clouds form
when excess water vapor in the atmosphere condenses to form ice and water droplets and precipitation.
A hydrocarbon that is a greenhouse gas with a global warming potential most recently estimated at 23
times that of carbon dioxide (CO2). Methane is produced through anaerobic (without oxygen)
decomposition of waste in landfills, animal digestion, decomposition of animal wastes, production and
distribution of natural gas and petroleum, coal production, and incomplete fossil fuel combustion. (CH4)
is a greenhouse gas that remains in the atmosphere for approximately 9-15 years. Methane is over 20
times more effective in trapping heat in the atmosphere than carbon dioxide (CO2) over a 100-year period
and is emitted from a variety of natural and human-influenced sources. Human-influenced sources
include landfills, natural gas and petroleum systems, agricultural activities, coal mining, stationary and
mobile combustion, wastewater treatment, and certain industrial process.
The future
The rise in methane started more recently than the rise in carbon dioxide, and the process of removal
from the atmosphere is difficult to predict. However, without technological change further increases in
concentrations are inevitable.
A powerful greenhouse gas with a global warming potential of 296 times that of carbon dioxide (CO2).
Major sources of nitrous oxide include soil cultivation practices, especially the use of commercial and
organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning. Nitrous oxide
emission levels from a source can vary significantly from one country or region to another, depending on
many factors such as industrial and agricultural production characteristics, combustion technologies,
waste management practices, and climate. For example, heavy utilization of synthetic nitrogen fertilizers
in crop production typically results in significantly more N2O emissions from agricultural soils than that
occurring from less intensive, low-tillage techniques. Also, the presence or absence of control devices on
combustion sources, such as catalytic converters on automobiles, can have a significant affect on the
level of N2O emissions from these types of sources.
The future
Since the Industrial Revolution, the level of nitrous
oxide in the atmosphere has increased by 16%.Due
to the long time it spends in the atmosphere, the
nitrous oxide that we release today will still be
trapping heat well into the next century.
Chlorofluorocarbons or CFCs (also known as Freon) are non-toxic, non-flammable and noncarcinogenic. They contain fluorine atoms, carbon atoms and chlorine atoms. The 5 main CFCs include
CFC-11 (trichlorofluoromethane - CFCl3), CFC-12 (dichloro-difluoromethane - CF2Cl2), CFC-113
(trichloro-trifluoroethane - C2F3Cl3), CFC-114 (dichloro-tetrfluoroethane - C2F4Cl2), and CFC-115
(chloropentafluoroethane - C2F5Cl).
CFCs are widely used as coolants in refrigeration and air conditioners, as solvents in cleaners,
particularly for electronic circuit boards, as a blowing agents in the production of foam (for example fire
extinguishers), and as propellants in aerosols. Indeed, much of the modern lifestyle of the second half
of the 20th century had been made possible by the use of CFCs.
Man-made CFCs however, are the main cause
of stratospheric ozone depletion. CFCs have a
lifetime in the atmosphere of about 20 to 100
years, and consequently one free chlorine
atom from a CFC molecule can do a lot of
damage, destroying ozone molecules for a
long time. Although emissions of CFCs
around the developed world have largely
ceased due to international control
agreements, the damage to the stratospheric
ozone layer will continue well into the 21st
century.
Greenhouse gases emissions reached the highest level at the end of the 1980s. In the period of 1990-1994
there was a reduction by approximately 28%, and since the year 1995 the GHGs emissions have been at
approximately the same level. Total green gases emissions (expressed CO2 equivalents) in 2004 reached
51 046.16 Gg excluding the sinks from the sector of Landscape Use - Changes to landscape use and
forestry (LULUCF), which represents a reduction by almost 30% (22 000 Gg). Emissions, also known in
literature as the net emissions including the sinks in the LULUCF sector reached 46 795.27 Gg in 2004.
Total emissions excluding LULUCF dropped by 50 Gg, compared to 2003. This reduction represents
approximately 1%.
Methane (CH4) emissions in 2004 reached the level of 203.90 Gg, which is 7% less than the 2003 figures,
and 33% less than the reference year of 1990. Total N2O emissions in 2004 reached 13.15 Gg, which is a
slight increase compared to 2003; however, less by 33% than the reference year of 1990. N2O emissions
show a slightly rising tendency since 2000, reaching highest values in the reference time period. Overall,
we can say that greenhouse gases emissions show a decreasing tendency, with the exception of several
years, mainly as a consequence of reduction in industrial fertilisers and volume of livestock.
At the conference of signatories to the UN Framework Convention on Climate
Change in Kyoto, Japan, in December 1997, Slovakia bound itself to reduce the
production of greenhouse gases by 8% by 2008, compared to 1990. Today we can
say that Slovakia has a real potential to meet the above mentioned objectives.
www.epa.gov
http://www.ucar.edu/communications/newsreleases/2001/learnwe
b.html
http://www.umich.edu/~gs265/society/greenhouse.htm
www.enviroportal.sk
http://www.bbc.co.uk/climate/evidence/.shtml
http://www.greenpeace.org/raw/content/slovakia/press/reports/vstava-klimaticke-zmeny.pdf
http://www.ekoskola.sk/vzduch_atmosfera.htm
http://www.sappo.sk